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281.
用变色酸法测定废水中的甲醇 总被引:5,自引:0,他引:5
目前西南油气田一些监测站尚不具备用甲醇分析气相色谱法的相应能力,因此通过比色定量分析实验,用变色酸法测定废水中甲醇。研究结果表明:标准溶液在570 nm处吸光度最大;对甲醇含量为8 μg/mL的标准溶液,显色剂最佳用量为0.5 mL。按照实验方法配制标准系列,测定、统计、回归出甲醇标准曲线。该方法对甲醇的最低检出浓度为0.080 mg/L。加标回收结果表明,该方法的准确度和精密度均较好,由此确定了用变色酸法测定废水中甲醇的最佳反应条件。 相似文献
282.
Summary. Qualitative and quantitative differences among pear cultivars were found
in constitutive and Cacopsylla-induced volatiles, depending on
experimental treatment of the trees (i.e., uninfested and partly or
completely infested by psyllids). Blend differences were also found
between pear cultivars and wild-type pear, alder and hawthorn–the
latter trees are frequently present in pear orchard
hedgerows. ?Interesting differences were found in the presence of methyl
salicylate and (E,E)-α-farnesene, two compounds previously found to
mediate attraction of predatory bugs towards psyllid-infested pear
trees. Methyl salicylate is expressed constitutively and is induced
systemically by infestation in the whole plant of all four cultivars.
(E,E)-α-farnesene on the other hand showed also systemic induction in
Bartlett, NY10355 and Beurré Hardy, but in partially infested Conference
trees it was induced locally, only in herbivore-damaged leaves. No
methyl salicylate or (E,E)-α-farnesene were identified in honeydew. In
field collected headspace samples of alder leaves infested by aphids and
leaf beetles we found methyl salicylate but no (E,E)-α-farnesene,
whereas in uninfested hawthorn neither were identified. Insight in the
variability of damage-related pear volatiles will have important
implications for integrated pest management in the field.
Received 27 August 2002; accepted 28 November 2002
R1D="
Correspondence to: Petru Scutareanu, e-mail:scuterea@science.uva.nl 相似文献
283.
研究以平玻璃和毛玻璃为载体,用Sol gel法制备附载型TiO2/Glass光催化剂,并用H2SO4溶液浸泡制得TiO2 SO2-4/Glass光催化剂。考察了光催化剂对甲基橙溶液的光催化性能。结果表明:平玻璃附载TiO2的光催化活性低于毛玻璃附载TiO2的光催化活性。且毛玻璃附载TiO2经连续6次使用后光催化活性基本不变。毛玻璃附载TiO2经H2SO4溶液处理后光催化活性明显升高。 相似文献
284.
285.
水质稳定剂生产过程中产生高浓度的甲醇废水,采用精馏法对甲醇废水进行预处理,一方面降低废水CODcr浓度,另处还回收甲醇,工程实践表明:该方法可以在相对较低的运转费用下保证CODcr的去除率在99.5%以上,为后续好氧生物降解创造有利条件。 相似文献
286.
WANG Jun GUO Bao-dong ZHANG Zhao-hong ZHANG Xiang-dong WU Jing LI Hong 《环境科学学报(英文版)》2005,17(3):414-418
The nanometer and ordinary anatase titanium dioxide(TiO2 ) powders were adopted as the sonocatalysts for the degradation of methyl orange used as a model compound for the first time. It was found that the sonocatalytic degradation effect of methyl orange in the presence of TiO2 powder were much better than that without TiO2, but the sonocatalytic activity of the nanometer anatase TiO2 particle was obviously higher than that of ordinary anatase TiO2 particle. Although there are many factors influencing sonocatalytic degradation of methyl orange, the experimental results showed that the best degradation ratio of methyl orange could be obtained when the experimental conditions were: initial concentration 15 mg/L, nanometer anatase TiO2 adding amount 750 mg/L, ultrasonic frequency 40 kHz, output power 50 W, pH = 3.0 and temperature 40℃ within 150 min. In addition, the catalytic activity of reused nanometer anatase TiO2 catalyst was also studied and found to decline gradually comparing with initial nanometer anatase TiO2 catalyst. All experiments indicated that the method of the sonocatalytic degradation of organic pollutants in the presence of TiO2 powder was an advisable choice for non-or lowtransparent organic wastewaters. 相似文献
287.
288.
Summary. Sensitivities to methyl eugenol of three sibling species in the Bactrocera dorsalis complex were compared. The degree of species sensitivity to methyl eugenol, i.e. B. dorsalis > B. papayae > B. carambolae (in decreasing order), was concomitant with the species age-related response to methyl eugenol as previously reported. The
ability to consume methyl eugenol by the three sibling species showed similar trend - the average ME consumption per male
was 0.70 ml for B. dorsalis, 0.58 ml B. papayae and 0.18 μl B. carambolae. Results obtained were discussed in relation to area-wide control of fruit fly.
Received 21 April 2002; accepted 9 July 2002 相似文献
289.
大气中存在的卤代甲烷对臭氧层具有极强的破坏作用并参与其它气候现象,其动态变化对臭氧的恢复和地球生态系统有重要影响。文章概述了全球变化下卤代甲烷源汇的研究情况并简单探索其进一步的研究方向。几种卤代甲烷中,溴代甲烷源汇最复杂且对臭氧具有最强的破坏力,因此研究较多。已证明CH3Br的来源有:海洋、土壤、生物燃烧、陆地植物和沼泽地的释放等;CH3Br的汇包括:光化学分解、被土壤和植物吸收、在海洋中的化学和生物降解等。但事实上是已知汇远远大于已知源,且各个源汇的通量在不同研究中结果差异较大,归其原因是卤代甲烷释放与吸收机制的不确定性。虽然近几年的研究也应用了稳定同位素示踪技术,但卤代甲烷各源汇的具体贡献并不清楚。今后卤代甲烷源汇的研究重点应放在与气体产生机制最密切的地下部分即“地下生态学”对其通量的影响,而同位素技术的改进及其在痕量气体研究中的应用也将是未来的重点方向。 相似文献
290.
In China, endemic arseniasis attributable to the geological-geochemistry environment is mainly found in the plain of the Great Bend of the Yellow River and the Hu-Bao plain in the Inner Mongolia Autonomous Region, in the Datong basin of Shanxi Province, the floodplain of the northern side of the Tian Mountain of Xinjiang Uygur Autonomous Region, and in the southwest coastal plain of Taiwan. These areas share many similar characteristics including widespread occurrences, a large population being affected, and the magnitude of risk involved. The population living in these areas is estimated to be around 5.5 × 105, of which of 2.5 × 105 are resident in Inner Mongolia. Based on our systematic research and comparison of various areas, we found the different types of arseniasis are often associated with different regions. The neural arseniasis is distributed in Xinjiang Uygur Autonomous Region and Shanxi Province, caused by inorganic arsenic in drinking water while the cycling-obstacle arseniasis is mainly found in Inner Mongolia and Taiwan, associated with organic arsenic in water. The distribution of arsenic affected villages in Inner Mongolia exhibits orientation and focus on low-lying land in the subsiding centre of the Great Bend basin, which was enriched with humus in the lake and limnetic deposits. Much CH4 gas can be detected in the water of shallow and deep wells in these villages. Some of the wells with higher concentrations of CH4 can even be ignited. This is a typical reductive geochemical environment. We tested the total amount of arsenic (As), As3+, and methyl arsenate in all types of water sources. It is found that the number of arseniasis cases is not clearly related to the total amount of arsenic (As) in the water. However, it is related to the ratio of As3+ plus methyl arsenic to the total amount of arsenic (As). The higher the ratio, the higher the number of people affected and the more serious the illness. The statistical results also indicate that good drinking water accounts for 60% of the drinking water source while the arsenic contaminated water makes up about 25% of the drinking water in the study area. This research reveals that the local geochemical environment is responsible for the spreading of the endemic arseniasis in the area and thus suggests a new direction of how to prevent such disease. 相似文献